How does this affect Idaho’s national ranking? Too early to say. Those rankings come from the U.S. Department of Education, which didn’t release state-by-state data for 2013-14 until last December.

What’s the dropout rate? Idaho’s dropout rate went down — albeit slightly. The 2014-15 dropout rate came in a 2.6 percent, compared to 2.9 percent in 2013-14.

Why the discrepancy between graduation rates and dropout rates? The 78.9 percent graduation rate does not include students who receive a GED, special education students who received a diploma under an adapted learning plan; and students who are earning graduation credits in an alternative school. It also doesn’t include students who fall through the bureaucratic cracks — such as students who transferred without proper paperwork.

None of these students are incorporated into the graduation rate — or the dropout rate.

How does Idaho calculate graduation rates? The 2014-15 numbers reflect a change in the way Idaho calculates its graduation rates — a change that brings Idaho in line with national practice.

The state now tracks the four-year progress of students, from ninth grade on. In other words, the 2014-15 graduation rate reflects the percentage of students who entered ninth grade in 2011-12, and received a diploma within the four-year window.

And this is a new calculation, right? Yes.

For years, Idaho used a less rigorous method to track graduation rates — looking only at the percentage of 12th graders who graduated by the end of the school year.

Idaho used the four-year tracking process for the first time in 2013-14, resulting in a significant decline in the graduation rate.